Lighting display devices, such as light emitting diodes (LEDs), organic light emitting diodes (OLEDs), and the like using novel light sources have rapidly superseded existing light sources and have come to the forefront of light technology. The lighting display devices form a lighting display device package together with components such as reflectors, reflector cups, scramblers, housings, etc. The lighting display devices may efficiently utilize light by maximizing optical efficiency while having high reflectivity. To this end, it is desired for materials used for such a component to be able to withstand high temperatures and to minimize decreased whiteness due to reflection and yellowing.
Thermoplastic and thermal resistant polyester resins have been used as the materials for the lighting display devices. The thermoplastic and thermal resistant polyester resins can have minimal deformation and excellent discoloration resistance at high temperatures relative to other resins, but can also exhibit problems of reduced impact resistance.
To resolve the problems, compositions in which white pigments and fillers are added to the polyester resins have been developed. Reference is made, for example, to Korean patent laid-open publication No. 2012-0140332 A, which is directed to a polyester resin composition including a polyester resin defined therein, white pigment, and filler. However, such compositions also can have problems such as dramatically reduced impact strength and moldability depending on the amounts of the white pigments and the fillers, and decreased light stability at high temperatures during long term operations.
Therefore, in the thermoplastic polyester resins used for the components of the lighting display devices, there has been increasing demand for technologies to impart heat resistance to the polyester resins and improve light stability and discoloration resistance of the polyester resins even though exposed to light and heat for a long time, without decreasing moldability and mechanical properties.